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Old 10-23-2012, 07:25 AM
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best way to vent crankcase.

Im currently not running a pcv valve. I have 2 breathers on one valve cover. Im wondering if it would be better to run a typical pcv valve, or something different. Motor is around 450 hp chevy 383. Thanks for any help

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Old 10-23-2012, 11:28 PM
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engine vacuum will vent it.do you have room?
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Old 10-24-2012, 01:27 AM
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If your vehicle is not subject to emissions laws, then two breathers on one valve cover will do as much good as any other way to vent the crankcase. We used to put Moon breathers on the oil pan too.
moon breather | eBay
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Old 10-24-2012, 02:04 AM
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A lot of breathers can get rid of crank case blow by pressure! but a pcv or a vacuum equivalent, has the added advantage of removing particulates like moisture, acid vapors, gas vapors, the gasses that get by your rings from blow by! So they don't condense inside on the walls of the block,or on the crank, rods etc, and a pcv or other vacuum type evacuation system actually can add H.P. and longevity to the engine!

Jester
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Old 10-24-2012, 05:54 AM
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Do you have much blow by currently? In other words is there much oil or oil mist residue dripping from the breathers?

Ideally you would install a pcv valve in one cover, and a breather on the opposite cover.

Or, if you have an older engine the PCV could be on the oil filler neck on the intake, and again, a breather in a valve cover. That's the set-up I am using on my Model A Tudor. It has one of the moon breathers that "techinspector1" linked to above.

Hope that helps.


Last edited by lakeroadster; 10-24-2012 at 06:03 AM.
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Old 10-24-2012, 03:37 PM
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get a good bit of oil drip from the breathers currently. The are on like 4 inch tubes. I think its just mostly splash though. There are some baffles in the tubes. Morosso cast covers with breather tubes on one cover. Currrently no pcv valve in the other cover. i have to have the valve cover drilled for it. Ive been using the vacuum port on the carb to run brakes and such, but i ordered a low profile fitting to go into the intake vacuum port and clear the carb. Then that will run brakes and carb run pcv. Just didnt know if it was absolutely necessary or what.
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Old 10-24-2012, 04:49 PM
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I believe you have more than one choice-

1. You can make certian that you have adequate baffles under your current breathers.

2. You can run a breather tank(s)-this will put any oil deposits in a catch can (which tries to seperate the Oil from the air)-like this:

Breather System Installation - Popular Hot Rodding Magazine

3. The third way (which is used on some high-operformance street cars) is to use a vacuum pump, set at, say, 5 in. Vacuum to pull vacuum out of the crankcase, which not only takes care of your problem, it will also slow/stop any other leaks you may have-the upside to this is that you may see a few more ponies because your Rings are sealing better-

Here is one of the more popular pumps:

ACDelco 215-425 Air Pump : Amazon.com : Automotive ACDelco 215-425 Air Pump : Amazon.com : Automotive


Pumps used on Mustangs and Diesel pickups are also popular (and Audis', etc.)-

I know that many will dispute my opinion on this, but I am not a big PCV fan-it does pull oil mist/vapor into the Combustion chamber and burns it, but what about the deposits on the Intake Valves-it is a band-aid for emissions at best, a controlled vacuum leak at worst, IMO-
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Old 10-24-2012, 08:59 PM
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If you cant follow my first post,you can vent into the headers.weld a fitting into each header and use that on both sides,
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Old 10-25-2012, 07:14 AM
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35WINDOW,

Option 2: Very sanitary looking:

You can run a breather tank(s)-this will put any oil deposits in a catch can (which tries to seperate the Oil from the air)-like this:Breather System Installation - Popular Hot Rodding Magazine



3. The third way (which is used on some high-operformance street cars) is to use a vacuum pump, set at, say, 5 in. Vacuum to pull oil out of the crankcase.

With this set-up do you also use a catch can?
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Old 10-25-2012, 08:44 AM
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That is what I'm doing on my Car-I will probably use something like this:

Peterson Fluid Systems : Oil Tank Accessories

or this:

Moroso : Category Display


Here is a little more on the subject-not all applies (although it is for a Race car which runs much higher vacuum):

The Pros and Cons of Racing Vacuum Pumps


I will use an adjustable filtered vacuum relief valve (to let air in-something like this, but there are much cheaper ones):

Peterson Fluid Systems 08-0455 : Peterson Adjustable Vacuum Regulator

then, I bought a Star Machine baffle fitting (AN), which will be in the Valve Cover. that will be plumbed into the Vacuum/Oil seperator Tank, which the vacuum Pump will draw from-I will run a vacuum gauge inside the car to monitor-

I understand that the '01-'06 Mustangs ran an electric vacuum pump from the factory, and that a lot of guys are having good luck with them-

good luck-they're not for everyone (as they add complexity), but, done correctly you should have a leak-free engine compartment, and, hopefully, a few more horses under the hood-
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Old 10-30-2012, 07:25 AM
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Quote:
Originally Posted by lakeroadster View Post
35WINDOW,

Option 2: Very sanitary looking:

You can run a breather tank(s)-this will put any oil deposits in a catch can (which tries to seperate the Oil from the air)-like this:Breather System Installation - Popular Hot Rodding Magazine



3. The third way (which is used on some high-operformance street cars) is to use a vacuum pump, set at, say, 5 in. Vacuum to pull oil out of the crankcase.

With this set-up do you also use a catch can?

With the catch can shown in the picture, wouldnt you want to plumb another line into the carb or other vacuum source? seems like there is not positive venting with this set up. (nothing sucking the air through) ? THerefore nothing is sucking the blowby and helping keep things sealed. am i wrong?
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Old 10-30-2012, 10:02 AM
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Quote:
Originally Posted by Lthompson View Post
With the catch can shown in the picture, wouldnt you want to plumb another line into the carb or other vacuum source? seems like there is not positive venting with this set up. (nothing sucking the air through) ? THerefore nothing is sucking the blowby and helping keep things sealed. am i wrong?
The best way I can think of to describe this setup is that this is like the old draft tube setup except that it is filtered-PCV's were an early attempt at emissions (and IMHO, a bad one at that)--

This setup simply allows the crankcase pumping to vent itself-a PCV recirculates these gasses (which you don't need on a performance engine)-now, if you want "positive venting", use a vacuum pump -

I do want to say that you can run a PCV, and that aren't "bad", I just think there are better ways-
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Old 10-30-2012, 11:28 AM
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Quote:
Originally Posted by vinniekq2 View Post
If you cant follow my first post,you can vent into the headers.weld a fitting into each header and use that on both sides,
Dont forget the GM style blowback valve, to keep the pressure going only one way.
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